Electron-tube circuit



Jan- 13, 1931- F. B. LLEWELLYN 15788532-r ELEGTRON TUBE CIRCUIT Filed July 30, 1926 *f2 9 www N ,4f/army.

Patented dan. 13, 1931 y tisana *d RRRDRRTCK R. LLnwnLLYN, or MoNToLAIR, NRW JERSEY, nssIGNoRToBnLL TELE- PHONE LaRoRaToRrns, INCORPORATED, or NEW YORK, N. Y., A CORPORATION or NEW YORK ELncTRoN-TUBR CIRCUIT Application 1ed,.Tu1y $0,

component is derived, and to prevent thel presence of fluctuations in the output circuit by impressing upon the input` circuit fluctuations Jfrom the same source in opposite phase. p l -Anderson, No. 1,541,311, June 9, 1925. Ac# cording to this patent input and output circuit networls are associated withV the energizing source and so designed and arrangedthat potential applied by one of them to the input circuit acts to neutralize potential applied by the'otherto the output circuit; but in order to provide anormal flow of space current in the output circuit a separate source or biasing potentialffor the input cir'- cuit is necessary, as the networks cause neutralization oi steady as well as variable po-V tential components set upin the two circuits rom the main energizing source.

The present invention eliminates the necessity for a separate source of biasing potential. 1This is accomplished by so designing the networks in the input and output circuits that the ratio of the iiuctuating po# tential components in the two circuits is such as to prevent a fluctuating current ink the output circuit, but the steady potential components are given a ditierent ratio, whereby there is a normal flow of space current of desired amount in the output circuit.

In another aspect this invention comprises a space discharge devicearranged as above described forsmoothing out the output wave of a rectier. The current from a rectifier thus controlled by space discharge device will be free of ripples and may he used directly for energizing other devices, such as other tubes, for example.

rlhe invention 'pertains also to the elimination of fluctuations in the output circuit of a See U. S. patent to S. E;

192e. serial No. 125,843.

thermionic deviceresulting from the use of alternating current vfor heating thecathode.

These fluctuations are particularly troublesome in a multi-stage amplifier in which luctuations produced in an early stage'are ainplitied in the subsequent stages.v -`When a themionic dischargedevice used asdescribed above for smoothing` outthe output of a rectifier is supplied with cathode heating Vcurrent from an alternating current source there f may be presentin its output a small alternating current component caused by the action of the heating current. In using the output energy of this .type of .device for energizing a multi-stage amplifier thisripple 1" may be balanced out in each stage by the use of the network arrangement above nientioned, s o proportioned as'to balance this ripple against Vthe variations produced by alternating current used for heating the cathode of such stage.

These and other` aspects and features ot the Vinvention willbe more readily under stood by reference to the following detailed description and claims in connection with the drawing in which: Fig. 1 shows one embodiment oie the invention in a circuit'for energizing a translating device in the form of a vacuum tube amplifier from an alternating current source; Fig. ,2, another embodiment of the invention in a multi-stage amplifier energized from a alternating current source; and Fig. 3, an embodiment of the invention in amulti-stage amplifier, and employing a tube for smoothing out lthe output'A of the rectifier. .r i y l, Fig. 1 shows a circuit adapted for amplifying" or detecting signals which are received through an input transformer?) and transmitted through a space discharge device 6 to an output transformer 7. The device 6 comprises the usual lamentary cathode 8,

grid 9 and plate 10. Alternating current is supplied `froIna source llthrough a transformer 12 having secondary windings 13 and 14 connected to a rectifier 15 and a secondary winding'l connected to the cathode 8 for supplying heating current thereto. Connected between theplate 10 andthe ,cathode 8 is a network 17 comprising a condenser 18 and a resistance 19 in series while between the grid 9 and the cathode 8 is connected a the plate 10, and the negative terminalA is` connected to the terminal of the network 2O adjacent 'the Vgrid 9. Connections to the cathode 8 are made at ltheInid-point ot the secondary winding 16 so as to prevent undue disturbances in the output circuit due to the alternating current supplied to Vthe filament. The space current circuitoi the device 6 may be traced from the anode l through the primary winding of the output transformerv 7 retard coil 24, the rectifier 15, resistance 21 to the cathode 8. The grid is maintained at a negative potential by theRI drop in resist- ,ance 21.. The values oi the elements of the networks 17 and 2O areso proportioned thatthe impedance of the network 17 is ,l times -the impedance of network 20 and of the saine phase characteristic, where a is the amplilcation constant ot the "device 6. Any ripple in the output of the rectifier which impresses a voltage E between the anode and cathode of the device 6 simultaneously impresses a voltage between the grid and cathode lso that no effect is produced in the output of the device 6 signal output of the device from feeding back into the input through the condenser and has no effect upon the noise level.

The condenser 18 makes the network 17 opaque to direct current so as not to balance out the direct current impressed upon the anode circuit. In order to prevent modulation of the signal by the alternating potential across the network 17 it is desirable that the impedance ot this network be low compared to the plate impedance of the tube.

Fig. 2 shows a multi-stage circuit comprising devices 26 and 27 connected in tandem l through an inter-stage transformer 28. The arrangement of this circuit is similar to that of Fig.. 1 with modications to adapt the circuit for two stage operations as noted below.V One grid balancing network 30 is used for both stages, though separate plate networks 31 and 32 are used. The impedance of the network 31 is made a times the impedance of vthe network 30 and the impedance of the network 32 is a times the impedance of the network 30 where a and a -are the amplification constants of the devices 26 and 27 respectively. If it is desired to use different grid biasing potentials for the two tubes sepi The retard coil 24 is merel)7 to prevent the arate grid circuit networks should be employed.

Separateretard coils 33 and 34 are provided in the plate circuits of the devices 26 and 27 respectively to prevent feed back not only from the output of one device 'to its input but also between stages. l l

Fig. 43 shows anampliier comprising two space discharge devices 35 andv36 connected in tandem through an interstage transformer'. Space current is derived by rectiying current from an alternating current source 37 in a rectilier tube 38. Current is supplied to the tube 38 through a transformer 39 having a primary winding 40 connected to the source 37 and secondary windings 41 and 42 connected to the tube 38. i v

A space discharge device 43 having a cathode 44, a grid 45 and an anode 46 is used for smoothing out the output of the rectifier. This device is arranged in a similar manner to the amplifier of Fig. lso that fluctuations in the space current supplied from the rectiiier 38 areV eliminated before the current reaches the output Vterminals 47, 48. Networks 49 and 50, similar to networksl7 aud 2O of Figl, are connected in the anode and grid circuits respectively. Network 5() is designed to have an 'impedance of the same phase angle characteristic but ot a value one over the amplilication constant of the tube 43 times the impedance of the network 49 so that the alternating current component of the output of the rectifier 38 is completely balanced out by the device 43. However, there may be an appreciable alternatrngcurrent component in the anode circuit of the device 43 due to the elect of the alternating current supplied from the secondari7 winding51 for heating the cathode 44.

, rlhe current at the output terminals 47, 48,

which is constant except for this iilament hum is supplied to the devices 35 and 3G across the two pai-rs ot `networks 52, 53, and 54, 55, respectively. These two pairs of networks function to balance this hum together with thehum produced in each device by the alternating current supplied from the secondaries 56 and 57 to the cathodes ot said devices 35 and 36,.respectively.

For example, in device 35 the hum'in the output of device 43 is vectorially added, iu the network 53, to the hum produced b v the alternating current heating of the cathode to produce an alternating` current electromotive orce E. These two hums being produced in a similar manner bythe action oi the alternating current supplied to the ilaments ot the devices 43 and 35v are ot the same frequency. Therefore their vector sum can he balanced out by the alternating electromotive torce produced the network b v the hum in the output of the device 43. rlhis accomplished by designing the network 52 so that the product o'fits impedance and the hum leo lll)

l'ZO

current in theoutput of device 43 is equal to l/,u times the product of the impedance of network 53 and the vector 'sun'f of the hum current in thek output otdevice land that developed by device 35, whereji is the amplification factor of the device ing current in the output circuit of device 35 will therefore be tree ofl all hum. y

Networks 54 and 55 are similarly designed to eliminate Vall hum from the output oli' device 36. Y

It is to be understood that the lcircuits Vdescribed may be variouslyinodified without departing from the spirit of the invention as deiined in the appended claims; for example, the arrangement shown in Fig. 3 for smoothing out the output of a rectifier is not limited in its use to the ciicuits of space discharge devices.

vWhat is claimed is:

l. In combination, a translating device having an anode, a cathode and a control element, a source of fluctuating potential for energizing said device, and means for supH plying to sai d control element and said anodeI potentials proportional to the fluctuating component of said source and hea ringa deft nite predetermined ratio to one another while supplying from said source to said anode and said control element direct current potentials having a. ratio different than said iirst ratio.

2. In combination, a space discharge device having an anode, a cathoderand a control electrode, a source of fluctuating potential for energizing said device, and means for applying potentials proportional to the iiuctuating component of said source, of diiier-` ing phase and havinga ratio proportional to the amplification constant` of Vsaid device to said control electrode and said anode, respec tively, while supplying .from said source to said anode a direct current potential `and to said control electrode a second direct current poten .,l, said last potentials having a ratio diliering from said first ratio.

3. In combination, a space discharge device having an anode, a cathode and a control electrode, a source of fluctuating potential for energizing said device, an impedance network opaque to direct current connected between said anode and cathode, a second impedance network connected between said control electrode and cathode, the impedance of said second network being one over the amplification constant of said device times the impedance of the first network, and connections from the terminal of said first network adjacent said anode and the terminal ot said second network adj acent the` control electrode to said source, the direct current impedance of said second network being substantially7 less than infinity.

4. In combination, a space discharge device having a cathode, an anode and a control electrode, a source of fluctuating potential for .energizing said device, an impedance path .The result!l comprising aresistance and avcondenser in v series connected between said anode and cathode, a second impedance path,comprising a resistanceand a condenser inseries with each other and a resistance in 'shunt thereto connected between said control electrode and said cathode, theinipedance of said second path being one over the amplification constant of said device times'tlieimpedance of ysaid first impedance path, and connections smoothing out the potential from said source,

comprising a space dischargedevice having a cathode, -a controlV electrode and an anode, and means for applying from said source po-V tentials of opposite phase and having a ratio of one over the amplification lconstant of said Y device Yto said control electrode and said anode, respectively, whereby the space current of said device is maintained substantially constant, and connections from the output of said device'for supplying a constant potential'to said utilization circuit. v

-6. In combination, a source of fluctuating potential, a utilizationcircuit, means for smoothing out the potential of said source comprising a space discharge device having ,a cathode,a control electrode and anianode, and means including a resistance connected in series with said source between said anode and cathode for applying potentials of opposite phase, proportional to the fluctuating `component of said source and having a ratio of one over the amplification constant of said device to said control electrode and anode, respectively, while applying to said anode a direct current potential and to said control electrode a second direct current potential proportional to the RI drop in saidresistance and of a value less than one over the amplification constant oi' the tube times said direct current potential applied to the anode, and connections from the output of said device to said utilization circuit for supplying constant current thereto.

7. In combination, a source of fluctuating potential, a utilization circuit, means for smoothing out the output current of said source, said means comprising a space discharge device having a cathode, a control electrode and an anode, an impedance network opaque to direct current connected between said anode and cathode, a second impedance network having an impedance of one over the amplification rconstant of said device times the impedance of said first network connected between the control electrode and the cathode,

connections from the terminal of said first network adjacent the anode and the terminal of said second network adjacent the control electrode to said source, and connections from the output circuit lof said device to said utilization circuit for supplying a constant current thereto. i L 8. A combination according to claim 7 in which said irst network comprises a resistance and a condenser in series, and said second network aresistance and a condenser in series` with each other and a resistance in shunt thereto.

9. In combination, a space discharge dcvice having athermionic cathode, a control electrode and an anode, a source of alternating cu 1rent tor energizing said device, connections 'for supplying heating current 'from said source to said cathode, a rectiier, connections for supplying current from said source to said vrectier,a second space fdischarge device having a thermionic'cathode, a control electrode and an anode,"connections for 4supplying Vheating current from said source to the cathode ot said second device, means for supplying from the output oit said rectifier potentials ot ditfering phase and having a ratio of one over the amplification constant of said second device to said control electrode and anode, respectively, whereby the space current of said second device is maintained independent of the fluctuations in the output of said rectiiier, an impedance network connected between the anode and cathode 'otsaid first device, a second impedance network connected between the control electrode and cathode of saidiirst device, and connections from the output of said second device to the terminal ot said. first network adjacent the anode and to the terminal ot said second network adjacent the control electrode lfor supplying space current to said irst device, the impedances oitV sai d networks being so proportioned that the potential across saidsecond network Vresulting from the electromotive force produced in said second device by the alternating currentapplied to the cathode is one over the amplitication constant of said first device times the potential across the second network resulting from the combined action ot the electroniotive torces produced in both of said devices by the alternating current supplied to the cathodes'thereot.

l0. A combination according to claim 9 in which the means for supplying potentials 'trom the lactiiier to the second device comprises a network opaque to direct current connected between the anode and cathode ot' said second device, a second network connected between the control electrode and cathode ot said second device and having an impedance one over the amplification constant of said second device times the im- ,pedance of said first network, and connections from said rectiiier to the terminal of said first network adjacent the anode, and

to the terminal of said lsecond networkadjaicent theV control electrode. Y

ll. fr combination according to claim 9 in which the firstV network comprises a resist-- ance and a condenserr inseries, and the second network, a resistanceand condenser in series with each other anda resistance in shunt thereto. Y

12A combination according to claim 9 in which the .means for supplying Vpotentials from the rectifier to the second device oomprises a resistance and condenser connected in series between the anode and cathode, a resistance and a condenser. in series with each other and a resistance in shunt thereto connected between the control electrode and the cathode, and connections from said rectier to the anode and control electrode of I said second device, and the rst network comprises a resistance and condenser in series for energizing said device, an impedance path connected between the .anode and cathode of said device, a second impedance path connected between the control electrode and cathode of said device, and connections from said source to the terminal of said first network adjacent the anode and to the terminalfof said second network adjacent the control electrode, the impedances of said networks being so proportioned that potentials proportional to the alternating current component of said iiuctuating potential and having a ratio of one over the ampliiioation constant of said device are applied to the control electrode and the anode, respectively, and that the direct current potential applied to the control electrode is less than one over he amplification factor times the direct current potential applied to theanode.

In witness whereof, I hereunto subscribe my name this 27th day of July A. D., 1926.

FREDERICK kB. LLEWELLYN.

EGO 

